Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state.
[3] At the beginning of soil formation, the bare rock outcrops are gradually colonized by pioneer species (lichens and mosses).
[5] Regardless of its name, the equilibrium stage of primary succession is the highest natural form of development that the environmental factors are capable of producing.
The same soil may achieve several successive steady state conditions during its existence, as exhibited by the Pygmy forest sequence in Mendocino County, California.
The climate role in the deterioration of the rocks and the formation of soils lead to the formulation of the theory of the biorhexistasy.
In this latter case, erosion is responsible for the destruction of the upper horizons of the ground, and is at the origin of a phenomenon of reversion to pioneer conditions.
For example, the clearing of an inclined ground, subjected to violent rains, can lead to the complete destruction of the soil.
Man can deeply modify the evolution of the soils by direct and brutal action, such as clearing, abusive cuts, forest pasture, litters raking.
However, these techniques will never totally succeed to restore a soil (and the fauna and flora associated to it) that took more than a 1000 years to build up.
[2] When productivity declined in the low-clay soils of northern Thailand, farmers initially responded by adding organic matter from termite mounds, but this was unsustainable in the long-term.
More work showed that applying bentonite to degraded sandy soils reduced the risk of crop failure during drought years.